Light-emitting diode (LED) light sources are commonly and widely used for direct-lit backlight illumination. Computers, personal digital assistants (PDAs), mobile phones, and thin liquid crystal display (LCD) televisions (TVs) are a few examples of backlight screen devices that use direct-lit LED backlights. However, the light intensity distribution range of LEDs is narrow, so a lens may be used on an LED to help distribute the light.
In direct-lit backlight, an array of lenses is placed in front of the light sources to provide a more uniform light output on the surface of the backlight device. A large number of LEDs may be needed depending on the size of the light spot right above the lens or if the radian angle of the lens is narrow, thus increasing the cost. The number of LEDs needed for a backlight can be decreased by increasing the spot size of each individual LED device.